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Year 6 Maths — Understanding elementary shapes

Classify angles by size, triangles by their sides and their angles, and tell flat shapes from solid ones.

Name: ________________________

Before you start

Four angles, drawn side by side and getting wider as you go. Find out what each one is called.

1234
  1. 1. Acute
  2. 2. Right angle
  3. 3. Obtuse
  4. 4. Straight

Acute is under 90°, obtuse is over it, and the straight one is a half turn — 180°, which is why it stopped looking like a corner at all.

  1. 1.Put these kinds of angle in order by size, smallest first.

    • Obtuse
    • Right
    • Acute
    • Straight
    • Reflex

  2. 2.This triangle has one right angle. Tap the corner where it is.

    Write the number of the part.

    123

  3. 3.The angles of a triangle add up to 180°. Two of them are 55° and 65°. How big is the third, in degrees?

  4. 4.Two right angles side by side make a straight angle. How many degrees is a straight angle?

  5. 5.All three angles of an equilateral triangle are equal, and they add up to 180°. How big is each one, in degrees?

  6. 6.A triangle with one angle of exactly 90° is called which kind of triangle?

    • a) Right-angled
    • b) Obtuse-angled
    • c) Equilateral
    • d) Acute-angled

  7. 7.Sort each shape by whether it is flat or solid.

    Groups: Flat shape · Solid shape

    • Sphere
    • Triangle
    • Cylinder
    • Circle
    • Square
    • Cube

  8. 8.A triangle has sides of 5 cm, 5 cm and 8 cm. How many of its sides are equal in length?

Answer key — Year 6 Maths — Understanding elementary shapes

  1. 1. 1. Acute 2. Right 3. Obtuse 4. Straight 5. Reflex
  2. 2. 2 — the bottom left corner
  3. 3. 60
  4. 4. 180
  5. 5. 60
  6. 6. a) Right-angled
  7. 7. Square → Flat shape; Cube → Solid shape; Circle → Flat shape; Sphere → Solid shape; Triangle → Flat shape; Cylinder → Solid shape
  8. 8. 2